"I can wait until when you have time."
I mean I can wait for you, until whenever you have time for me. Is that the right way to say it?
"I can wait until when you have time."
I mean I can wait for you, until whenever you have time for me. Is that the right way to say it?
Yes, it sounds weird. Correct is
I can wait until you have time.
The word until plays two roles. It can be a preposition, which takes a noun or a noun phrase:
Stay at home until Thursday.
Wait until the first snows of winter.
Or it can be a conjunction, joining two finite clauses:
We will fight until we die.
I can wait until you have time.
But it can't take an adverbial phrase. So these are wrong:
I can wait until when you have time.
Stay at home until on Thursday.
I hope this is clear! As a bonus, the words before and after follow the same rules as until.